Conventionally, the brake devices in railroad vehicles have been provided with pressure control valves equipped with solenoid valves, in which a solenoid valve outputting brake command pressure matched with a brake pressure command signal output by a brake receiver is integrated with a pressure control valve, for example, a relay valve. Such pressure control valve receives the brake command pressure output by the solenoid valve, in a command pressure chamber in the form of pilot pressure and subjects such brake command pressure to volume amplification before outputting it to a brake cylinder. Such a system is taught, for example, in Japanese Laid-Open Utility Model Application H.
In this pressure control valve equipped with a solenoid valve, the main valve body is provided with an air-supply chamber connected to a pressurized air source, a control pressure chamber into which the pilot pressure from the solenoid valve is input, an output chamber connected to the brake cylinder, and air-supply valve which selectively establishes contact between and isolates such air-supply chamber and output chamber. Such control valve further includes a pressure-adjusting piston which is urged one way by a pressure-adjusting spring and is urged the other way by the pilot pressure of the control pressure chamber. Additionally, there is a hollow exhaust valve rod provided integrally with this pressure-adjusting piston. The air-supply valve is opened or closed depending on the pilot pressure input into the control pressure chamber, and thus the compressed air supplied to the air-supply chamber can be supplied to the brake cylinder at a pressure corresponding to the pilot pressure.
Now, in such conventional pressure control valves equipped with a solenoid valve, such solenoid valve, which supplies the pilot pressure to the control pressure chamber, is disposed to the side of the main valve body. Thus, the projected planar surface area is large and a large amount of space is needed when it is mounted below the floor of a vehicle. There is, therefore, a problem in that the space below the floor of the vehicle cannot be used efficiently.